1. Field of the Invention
The present invention relates to a luminescent screen, and more particularly to a luminescent screen having a screen plate containing a substance capable of emitting light in response to stimulating light applied thereto.
2. Description of the Prior Art
There are known display systems having a luminescent screen comprising a screen plate which contains a substance (a luminescent substance) capable of fluorescence or phosphorescence in response to stimulating light such as ultraviolet radiation, visible light, near-infrared radiation, or the like, the fluorescent substance comprising a piperidinium tetra (benzoyltrifluoroacetone) europium complex, for example. The stimulating light is applied to the screen plate to enable the screen plate to display an image.
Heretofore, the screen plate has generally been in the form of a flat plastic plate. As shown in FIG. 1 of the accompanying drawings, when stimulating light is applied to a plastic screen plate 20, luminescent light is emitted from a luminescent substance (indicated by a star-shaped symbol) and scattered in every direction as indicated by the broken lines. More specifically, the emitted luminescent light is directed toward display and reverse surfaces of the screen, and also propagated in the screen plate 20. Therefore, The efficiency with which the applied stimulating light is utilized is low, and the intensity of luminescent light emitted toward the display side of the screen plate is so low that the screen as viewed by the viewer is relatively dark.